METHAMPHETAMINE . . .on Wipes by Liquid-Liquid Extraction: METHOD 9106, Issue 1, dated 17 October 2011 - Page 15 of 31
Table 6. Example of mass spectrometer operation parameters for selected ion monitoring mode.(1) Chlorodifluoroacetyl derivatives Scan window(2) Acquisition ions (m/z) per group(3) Acquisition Group 1 10.5 to 13.0 104 118 128 156 160 170 172 177 Acquisition Group 2 13.0 to 15.2 104 156 158 170 172 198 296 Acquisition Group 3 15.2 to 18.0 109 135 162 170 184 194 200 242 (6) (7) GC Peak Retention Time Primary Ion (m/z) Secondary ion and approximate relative abundance(8) (4) (5) No. Target Analytes and Internal Standards: (min) (Quantification Ion) (relative to the Primary Ion) Acquisition Group 1 85% 2 Amphetamine-D11 (I$)(9) 11.07 160 128 85% 3 Amphetamine 11.15 156 118 33% 5 Phentermine 11.34 170 172 95% 8 n-Methyl phenethylamine (I$)(9) 12.20 156 104 32% 9 Methamphetamine-D14 (I$)(9) 12.51 177 128 32% 10 Methamphetamine 12.61 170 118 Acquisition Group 2: 18 Phenylpropanolamine 13.27 156 246 25% 20 Dibromooctafluorobiphenyl(10) 13.63 296 456 115% 21 N-n-Propylamphetamine (I$)(9) 13.8 198 156 75% 25 Ephedrine 14.27 170 172 33% 28 Pseudoephedrine 14.74 170 172 33% Acquisition Group 3: 32 Caffeine 15.66 194 109 50% 40 Phencyclidine 16.41 200 242 35% 41 MDMA 16.48 170 162 95% 43 MDEA 16.87 184 162 75% (1) In this example, 10 analytes and 5 internal standards are grouped into 3 acquisition groups having no more than 8 primary and secondary ions per acquisition group. For 6 analytes and internal standards or less, one acquisition group may be sufficient. (2) Scan window is in minutes. Actual times are dependant upon GC column and instrument conditions. (3) Ions (m/z) in bold numbers are suggested primary (quantification) ions. For best signal to noise ratio, do not exceed 10 ions per acquisition group. Dwell times per ion (m/z) is 50 milliseconds. (4) GC peak numbers are those in Figure 1 and Table 10. (5) The list of analytes and internal standards shown is an example. Analyte(s) and internal standard(s) must be selected according to analytical objectives. (6) Retention times are dependant upon GC column and instrument conditions. (7) The better ions for quantification are usually the base peak or those with masses >100 m/z and relative abundances >50% of the base peak. These minimize interference from co-eluting hydrocarbons. The suggested primary ions are not necessarily the base peaks in the mass spectra of the analytes, especially if the base peaks are ions common to aromatics (e.g. m/z 91) and paraffinic or olefinic hydrocarbons (e.g. m/z 42, 57, and 58). Suggested ions for other analytes and internal standards are given in Tables 9 and 10. (8) Secondary ions may be used for quantification if the primary ion encounters interference. Secondary ions improve qualitative identification for SIM analyses. The relative abundances given are approximate (±10 to 20%) and depend upon specific instrument tuning and conditions. They are relative to the primary ion and not necessarily to the base peak in the mass spectrum of each analyte. The relative abundance of secondary ions for each analyte needs to be determined from a mass spectrum acquired on the instrument to be used. (9) (I$) = internal standard. Internal standards must be paired with the appropriate analytes. Tables 8a and 8b give precision and accuracy data for various pairings. Other potentially useful internal standards are given in Table 9. Highly deuterated analogs of the target analytes are preferred, where available. (10) Dibromooctafluorobiphenyl is an optional secondary internal standard useful for monitoring autosampler performance and instrument tuning. A shift in the mass axes or the relative abundance of m/z 296 to that of m/z 456 throughout an analytical sequence will help signal degraded tuning.
NIOSH Manual of Analytical Methods (NMAM), Fifth Edition
Method rev. 1.1.1
